refactor: extract shared helpers to deduplicate repeated code patterns (#7917)

* refactor: add shared helper modules for code deduplication

New modules:
- gateway/platforms/helpers.py: MessageDeduplicator, TextBatchAggregator,
  strip_markdown, ThreadParticipationTracker, redact_phone
- hermes_cli/cli_output.py: print_info/success/warning/error, prompt helpers
- tools/path_security.py: validate_within_dir, has_traversal_component
- utils.py additions: safe_json_loads, read_json_file, read_jsonl,
  append_jsonl, env_str/lower/int/bool helpers
- hermes_constants.py additions: get_config_path, get_skills_dir,
  get_logs_dir, get_env_path

* refactor: migrate gateway adapters to shared helpers

- MessageDeduplicator: discord, slack, dingtalk, wecom, weixin, mattermost
- strip_markdown: bluebubbles, feishu, sms
- redact_phone: sms, signal
- ThreadParticipationTracker: discord, matrix
- _acquire/_release_platform_lock: telegram, discord, slack, whatsapp,
  signal, weixin

Net -316 lines across 19 files.

* refactor: migrate CLI modules to shared helpers

- tools_config.py: use cli_output print/prompt + curses_radiolist (-117 lines)
- setup.py: use cli_output print helpers + curses_radiolist (-101 lines)
- mcp_config.py: use cli_output prompt (-15 lines)
- memory_setup.py: use curses_radiolist (-86 lines)

Net -263 lines across 5 files.

* refactor: migrate to shared utility helpers

- safe_json_loads: agent/display.py (4 sites)
- get_config_path: skill_utils.py, hermes_logging.py, hermes_time.py
- get_skills_dir: skill_utils.py, prompt_builder.py
- Token estimation dedup: skills_tool.py imports from model_metadata
- Path security: skills_tool, cronjob_tools, skill_manager_tool, credential_files
- Non-atomic YAML writes: doctor.py, config.py now use atomic_yaml_write
- Platform dict: new platforms.py, skills_config + tools_config derive from it
- Anthropic key: new get_anthropic_key() in auth.py, used by doctor/status/config/main

* test: update tests for shared helper migrations

- test_dingtalk: use _dedup.is_duplicate() instead of _is_duplicate()
- test_mattermost: use _dedup instead of _seen_posts/_prune_seen
- test_signal: import redact_phone from helpers instead of signal
- test_discord_connect: _platform_lock_identity instead of _token_lock_identity
- test_telegram_conflict: updated lock error message format
- test_skill_manager_tool: 'escapes' instead of 'boundary' in error msgs

tests/e2e/conftest.py

@@ -211,7 +211,8 @@ def make_adapter(platform: Platform, runner=None):
     config = PlatformConfig(enabled=True, token="e2e-test-token")
 
     if platform == Platform.DISCORD:
-        with patch.object(DiscordAdapter, "_load_participated_threads", return_value=set()):
+        from gateway.platforms.helpers import ThreadParticipationTracker
+        with patch.object(ThreadParticipationTracker, "_load", return_value=set()):
             adapter = DiscordAdapter(config)
         platform_key = Platform.DISCORD
     elif platform == Platform.SLACK: